Biochemistry (Moscow) (v.83, #9)

Different Pathways to Neurodegeneration by E. I. Rogaev (1007-1008).
The current issue is dedicated to the studies of neurodegenerative diseases and memory. Molecular mechanisms and mutant genes have already been revealed for many neurodegenerative diseases. However, in many cases the cause of selective death of neurons in different brain regions remains unclear. Genetic predisposition and aging are well established risk factors in many neurodegenerative diseases. A large body of evidence has been obtained that shows an important role of immune factors in the modulation of neurodegenerative processes. The progress in the treatment of neurodegenerative diseases requires new cell models for identification of non-canonical pharmacological targets and development of approaches for memory regulation. Gene therapy technologies based on genome editing and RNA interference methods are among promising approaches for repairing primary molecular defects underlying neurodegenerative pathologies.
Keywords: neurodegeneration; mutant genes; aging; memory; Alzheimer’s disease

Changes in Retinal Glial Cells with Age and during Development of Age-Related Macular Degeneration by D. V. Telegina; O. S. Kozhevnikova; N. G. Kolosova (1009-1017).
Age is the major risk factor in the age-related macular degeneration (AMD) which is a complex multifactor neurodegenerative disease of the retina and the main cause of irreversible vision loss in people over 60 years old. The major role in AMD pathogenesis belongs to structure-functional changes in the retinal pigment epithelium cells, while the onset and progression of AMD are commonly believed to be caused by the immune system dysfunctions. The role of retinal glial cells (Muller cells, astrocytes, and microglia) in AMD pathogenesis is studied much less. These cells maintain neurons and retinal vessels through the synthesis of neurotrophic and angiogenic factors, as well as perform supporting, separating, trophic, secretory, and immune functions. It is known that retinal glia experiences morphological and functional changes with age. Age-related impairments in the functional activity of glial cells are closely related to the changes in the expression of trophic factors that affect the status of all cell types in the retina. In this review, we summarized available literature data on the role of retinal macro- and microglia and on the contribution of these cells to AMD pathogenesis.
Keywords: aging; retina; age-related macular degeneration; astrocytes; Muller cells; microglia

Both plants and animals have adopted a common strategy of using ~18–25-nucleotide small non-coding RNAs (sncRNAs), known as microRNAs (miRNAs), to transmit DNA-based epigenetic information. miRNAs (i) shape the total transcriptional output of individual cells; (ii) regulate and fine-tune gene expression profiles of cell clusters, and (iii) modulate cell phenotype in response to environmental stimuli and stressors. These miRNAs, the smallest known carriers of geneencoded post-transcriptional regulatory information, not only regulate cellular function in healthy cells but also act as important mediators in the development of plant and animal diseases. Plants possess their own specific miRNAs; at least 32 plant species have been found to carry infectious sncRNAs called viroids, whose mechanisms of generation and functions are strikingly similar to those of miRNAs. This review highlights recent remarkable and sometimes controversial findings in miRNA signaling in plants and animals. Special attention is given to the intriguing possibility that dietary miRNAs and/or sncRNAs can function as mobile epigenetic and/or evolutionary linkers between different species and contribute to both intra- and interkingdom signaling. Wherever possible, emphasis has been placed on the relevance of these miRNAs to the development of human neurodegenerative diseases, such as Alzheimer’s disease. Based on the current available data, we suggest that such xeno-miRNAs may (i) contribute to the beneficial properties of medicinal plants, (ii) contribute to the negative properties of disease-causing or poisonous plants, and (iii) provide cross-species communication between kingdoms of living organisms involving multiple epigenetic and/or potentially pathogenic mechanisms associated with the onset and pathogenesis of various diseases.
Keywords: Alzheimer’s disease; inflammatory neurodegeneration; microRNA; plant miRNAs; small non-coding RNAs; viroids

Molecular Pathogenesis in Huntington’s Disease by S. N. Illarioshkin; S. A. Klyushnikov; V. A. Vigont; Yu. A. Seliverstov; E. V. Kaznacheyeva (1030-1039).
Huntington’s disease (HD) is a severe autosomal dominant neurodegenerative disorder characterized by a combination of motor, cognitive, and psychiatric symptoms, atrophy of the basal ganglia and the cerebral cortex, and inevitably progressive course resulting in death 5–20 years after manifestation of its symptoms. HD is caused by expansion of CAG repeats in the HTT gene, which leads to pathological elongation of the polyglutamine tract within the respective protein-huntingtin. In this review, we present a modern view on molecular biology of HD as a representative of the group of polyglutamine diseases, with an emphasis on conformational changes of mutant huntingtin, disturbances in its cellular processing, and proteolytic stress in degenerating neurons. Main pathogenetic mechanisms of neurodegeneration in HD are discussed in detail, such as systemic failure of transcription, mitochondrial dysfunction and suppression of energy metabolism, abnormalities of cytoskeleton and axonal transport, microglial inflammation, decrease in synthesis of brain-derived neurotrophic factor, etc.
Keywords: Huntington’s disease; molecular pathogenesis; polyglutamine expansion; proteolytic stress; transcription dysregulation; mitochondria

Genome Editing and the Problem of Tetraploidy in Cell Modeling of the Genetic Form of Parkinsonism by V. V. Simonova; A. S. Vetchinova; E. V. Novosadova; L. G. Khaspekov; S. N. Illarioshkin (1040-1045).
The prevalent form of familial parkinsonism is caused by mutations in the LRRK2 gene encoding for the mitochondrial protein kinase. In the review, we discuss possible causes of appearance of tetraploid cells in neuronal precursors obtained from induced pluripotent stem cells from patients with the LRRK2-associated form of parkinsonism after genome editing procedure. As LRRK2 protein participates in cell proliferation and maintenance of the nuclear envelope, spindle fibers, and cytoskeleton, mutations in the LRRK2 gene can affect protein functions and lead, via various mechanisms, to the mitotic machinery disintegration and chromosomal aberration. These abnormalities can appear at different stages of fibroblast reprogramming; therefore, editing of the LRRK2 nucleotide sequence should be done during or before the reprogramming stage.
Keywords: parkinsonism; LRRK2 ; induced pluripotent stem cells; neuronal precursors; genome editing; tetraploidy

Studying pathogenesis of neurodegenerative diseases, including Parkinson’s disease (PD), requires adequate disease models. The available patient’s material is limited to biological fluids and post mortem brain samples. Disease modeling and drug screening can be done in animal models, although this approach has its own limitations, since laboratory animals do not suffer from many neurodegenerative diseases, including PD. The use of neurons obtained by targeted differentiation from induced pluripotent stem cells (iPSCs) with known genetic mutations, as well as from carriers of sporadic forms of the disease, will allow to elucidate new components of the molecular mechanisms of neurodegeneration. Such neuronal cultures can also serve as unique models for testing neuroprotective compounds and monitoring neurodegenerative changes against a background of various therapeutic interventions. In the future, dopaminergic neurons differentiated from iPSCs can be used for cell therapy of PD.
Keywords: Parkinson’s disease; induced pluripotent stem cells; cell model; cell therapy; dopaminergic neurons; isogenic system

Anti-amyloid Therapy of Alzheimer’s Disease: Current State and Prospects by S. A. Kozin; E. P. Barykin; V. A. Mitkevich; A. A. Makarov (1057-1067).
Drug development for the treatment of Alzheimer’s disease (AD) has been for a long time focused on agents that were expected to support endogenous β-amyloid (Aβ) in a monomeric state and destroy soluble Aβ oligomers and insoluble Aβ aggregates. However, this strategy has failed over the last 20 years and was eventually abandoned. In this review, we propose a new approach to the anti-amyloid AD therapy based on the latest achievements in understanding molecular causes of cerebral amyloidosis in AD animal models.
Keywords: Alzheimer’s disease; amyloid-β; isoaspartate; zinc; protein-protein complexes; cerebral β-amyloidosis

Dynamic Microtubules in Alzheimer’s Disease: Association with Dendritic Spine Pathology by E. I. Pchitskaya; V. A. Zhemkov; I. B. Bezprozvanny (1068-1074).
Alzheimer’s disease (AD) is the most common incurable neurodegenerative disorder that affects the processes of memory formation and storage. The loss of dendritic spines and alteration in their morphology in AD correlate with the extent of patient’s cognitive decline. Tubulin had been believed to be restricted to dendritic shafts, until recent studies demonstrated that dynamically growing tubulin microtubules enter dendritic spines and promote their maturation. Abnormalities of tubulin cytoskeleton may contribute to the process of dendritic spine shape alteration and their subsequent loss in AD. In this review, association between tubulin cytoskeleton dynamics and dendritic spine morphology is discussed in the context of dendritic spine alterations in AD. Potential implications of these findings for the development of AD therapy are proposed.
Keywords: Alzheimer’s disease; dendritic spines; tubulin; microtubule dynamics; EB3

Genetic Association between Alzheimer’s Disease Risk Variant of the PICALM Gene and Auditory Event-Related Potentials in Aging by N. V. Ponomareva; T. V. Andreeva; M. A. Protasova; Yu. V. Filippova; E. P. Kolesnikova; V. F. Fokin; S. N. Illarioshkin; E. I. Rogaev (1075-1082).
Aging and genetic predisposition are major risk factors in age-related neurodegenerative disorders. The most common neurodegenerative disorder is Alzheimer’s disease (AD). Genome-wide association studies (GWAS) have identified statistically significant association of the PICALM rs3851179 polymorphism with AD. The PICALM G allele increases the risk of AD, while the A allele has a protective effect. We examined the association of the PICALM rs3851179 polymorphism with parameters of the P3 component of auditory event-related potentials (ERPs) in 87 non-demented volunteers (age, 19–77 years) subdivided into two cohorts younger and older than 50 years of age. We found statistically significant association between the AD risk variant PICALM GG and increase in the P3 latency in subjects over 50 years old. The age-dependent increase in the P3 latency was more pronounced in the PICALM GG carriers than in the carriers of the PICALM AA and PICALM AG genotypes. The observed PICALM-associated changes in the neurophysiological processes indicate a decline in the information processing speed with aging due, probably, to neuronal dysfunction and subclinical neurodegeneration of the neuronal networks in the hippocampus and the frontal and parietal cortical areas. Such changes were less pronounced in the carriers of the PICALM gene A allele, which might explain the protective effect of this allele in the cognitive decline and AD development.
Keywords: PICALM genotype; neurodegeneration; aging; genetic predisposition; Alzheimer’s disease; event-related potentials; P300

Mitochondria with Morphology Characteristic for Alzheimer’s Disease Patients Are Found in the Brain of OXYS Rats by M. A. Tyumentsev; N. A. Stefanova; E. V. Kiseleva; N. G. Kolosova (1083-1088).
Growing evidence suggests that mitochondrial dysfunction is closely linked to the pathogenesis of sporadic Alzheimer’s disease (AD). One of the key contributors to various aspects of AD pathogenesis, along with metabolic dysfunction, is mitochondrial dynamics, involving balance between fusion and fission, which regulates mitochondrial number and morphology in response to changes in cellular energy demand. Recently, Zhang et al. ((2016) Sci. Rep., 6, 18725) described a previously unknown mitochondrial phenotype manifesting as elongated chain-linked mitochondria termed “mitochondria-on-a-string” (MOAS) in brain tissue from AD patients and mouse models of AD. The authors associated this phenotype with fission arrest, but implications of MOAS formation in AD pathogenesis remain to be understood. Here we analyze the presence and number of MOAS in the brain of OXYS rats simulating key signs of sporadic AD. Using electron microscopy, we found MOAS in OXYS prefrontal cortex neuropil in all stages of AD-like pathology, including mani-festation (5-month-old rats) and progression (12–18-month-old rats). The most pronounced elevation of MOAS content (8–fold) in OXYS rats compared to Wistar controls was found at the preclinical stage (20 days) on the background of decreased numbers of non-MOAS elongated mitochondria. From the age of 20 days through 18 months, the percentage of MOAS-containing neuronal processes increased from 1.7 to 8.3% in Wistar and from 13.9 to 16% in OXYS rats. Our results support the importance of the disruption of mitochondrial dynamics in AD pathogenesis and corroborate the existence of a causal link between impaired mitochondrial dynamics and formation of the distinctive phenotype of “mitochondria-on-a-sting”.
Keywords: Alzheimer’s disease; mitochondrial dynamics; OXYS rats; electron microscopy

Cytokines as Mediators of Neuroinflammation in Experimental Autoimmune Encephalomyelitis by V. S. Gogoleva; K. -S. N. Atretkhany; M. S. Drutskaya; I. A. Mufazalov; A. A. Kruglov; S. A. Nedospasov (1089-1103).
Cytokines play a pivotal role in maintaining homeostasis of the immune system and in regulation of the immune response. Cytokine dysregulation is often associated with development of various pathological conditions, including autoimmunity. Recent studies have provided insights into the cytokine signaling pathways that are involved not only in pathogenesis of autoimmune neuroinflammatory disorders, such as multiple sclerosis, but also in neurodegenerative states, for example, Alzheimer’s disease. Understanding the exact molecular mechanisms of disease pathogenesis and evaluation of relevant experimental animal models are necessary for development of effective therapeutic approaches.
Keywords: experimental autoimmune encephalomyelitis; inflammation; neurodegeneration; proinflammatory cytokines; TNF; IL-6; IL-17A

Immunogenetic Factors of Neurodegenerative Diseases: The Role of HLA Class II by M. P. Aliseychik; T. V. Andreeva; E. I. Rogaev (1104-1116).
An increase in the life expectancy during the last decades in most world countries has resulted in the growing number of people suffering from neurodegenerative disorders, including Alzheimer’s disease, Parkinson’s disease, fron-totemporal dementia, and others. Familial forms of neurodegenerative diseases account for 5–10% of all cases and are caused by mutations in specific genes often resulting in pathological protein deposition. The risk factors for neurodegeneration include trauma, lifestyle, and allelic variants of disease-associated genes with incomplete penetrance. Many of these gene variants are located in immunity-related loci, particularly in the human leukocyte antigen locus (HLA class II) coding for proteins of the major histocompatibility complex class II (MHCII). HLA class II plays a key role in the antigen presentation and is expressed in microglial cells. Microglia is a component of innate immunity. On the one hand, microglial cells phagocytize pathological protein deposits; on the other hand, they produce proinflammatory factors accelerating neuronal death. The involvement of adaptive immunity mechanisms (antigen presentation, T cell response, antibody production) in the development of neurodegenerative diseases remains unclear and requires further research, including more detailed studies of the role of identified HLA class II genetic variants.
Keywords: human leukocyte antigen; major histocompatibility complex class II; neurodegeneration; Alzheimer’s disease; Parkinson’s disease; genome-wide association study

Impairment of protein synthesis in the brain during learning prevents memory consolidation and results in amnesia, which until recently has been regarded irreversible. However, in some cases impaired memory could be restored by various “reminder” stimuli. The present study is based on the hypothesis that even in behaviorally profound amnesia, some disintegrated fragments of the engram are preserved in the brain and could be re-integrated into the whole system by specific types of stimuli. The aim of the present study was to test this hypothesis in an experimental model of pharmacologically induced memory impairment in young chicks and to reveal the brain areas involved in this process by mapping of reminder-induced expression of transcriptional factors c-Fos and Egr-1. We show that reminder treatment results in the recovery of memory impaired by protein synthesis inhibition during learning and induces c-Fos and Egr-1 expression in the brain regions involved in learning in this behavioral model. The patterns of c-Fos and Egr-1 induced expression in animals with impaired memory differed from the patterns of animals with unimpaired memory and as well as naпve animals with no memory. Thus, analysis of activity-induced c-Fos and Egr-1 expression revealed the brain regions that were specifically activated by the reminder treatment. At the behavioral level, this treatment led to memory recovery. Altogether, these results suggest that the reminder-induced transcriptional activity in the brain of amnestic animals occurs in regions maintaining the engram fragments that reintegrate to recover the impaired memory.
Keywords: memory; amnesia; brain; engram; gene expression; c-Fos; Egr-1

Enhancement of Declarative Memory: From Genetic Regulation to Non-invasive Stimulation by D. V. Bryzgalov; I. L. Kuznetsova; E. I. Rogaev (1124-1138).
The problem of memory enhancement is extremely important in intellectual activity areas and therapy of different types of dementia, including Alzheimer’s disease (AD). The attempts to solve this problem have come from different research fields. In the first part of our review, we describe the results of targeting certain genes involved in memory-associated molecular pathways. The second part of the review is focused on the deep stimulation of brain structures that can slow down memory loss in AD. The third part describes the results of the use of non-invasive brain stimulation techniques for memory modulation, consolidation, and retrieval in healthy people and animal models. Integration of data from different research fields is essential for the development of efficient strategies for memory enhancement.
Keywords: memory; Alzheimer’s disease; brain stimulation; hippocampus; CREB pathway

Erratum to: “Amphipathic CRAC-Containing Peptides Derived from the Influenza Virus A M1 Protein Modulate Cholesterol-Dependent Activity of Cultured IC-21 Macrophages” by A. Ya. Dunina-Barkovskaya; Kh. S. Vishnyakova; A. O. Golovko; A. M. Arutyunyan; L. A. Baratova; O. V. Batishchev; V. A. Radyukhin (1139-1139).
On p. 982 in the list of authors instead of:O. V. BathishchevShould read:O. V. Batishchev